1. Technical Field of the Invention
The present invention relates generally to a double-shell closure. More particularly, the present invention relates to a double-shell closure having first and second intersecting triangles for cutting a container liner but which leaves a portion of the liner connected to the container rim such that the cut liner does not fall into the container and contact the product therein.
2. Description of the Related Art
Various closure designs are known which provide a piercing element in order to open a liner. However, the prior art patents fails to disclose a closure having a cutter formed of intersecting perpendicular triangles for opening a liner.
In view of currently known closures, it is preferable to have a closure which vents the internal product pressure when a container or package is initially opened while minimizing a consumer's exposure to the product dust produced from internal package pressure during initial package opening.
The present invention provides a double-shell closure for a container having a liner seal extending across a container rim sealing the container and allowing for build up of internal container pressure. The double-shell closure includes an outer skirt depending from a peripheral edge of a top wall and an inner skirt depending from the top wall. The inner skirt comprises at least one thread helically extending along an inner surface of the inner skirt. Extending along the outer surface of the inner skirt from the top wall downward are a plurality of strengthening ribs in a spaced apart relationship. In one exemplary configuration, the strengthening ribs are spaced apart about 11.25 degrees from each other but alternatively the strengthening ribs may be spaced apart in a plurality of configurations.
Along an upper portion of the outer shell are a plurality of knurls for aid in gripping the closure during removal and application of the closure to the container threads and when the closure is inverted for cutting the liner seal during initial opening of the container.
Depending from the lower edge portion of the closure outer skirt are diametrically opposed locking lugs. The locking lugs engage lugs on the container neck to provide a child resistance feature. The locking lugs may be substantially triangular in shape having an inner surface, a tapered deflection surface, and an engaging surface. During application of the closure to the container neck, each deflection surface cams against an inner surface of the container neck locking lug deflecting the closure lugs inward and causing ovalized flexing of the closure outer skirt. The strengthening ribs inhibit any flexing of the inner skirt. Once the closure lugs pass by the container lugs the closure returns to its circular shape and the engaging surface of the closure lug engages the container neck lug so that the closure may not back-off. The engaging surface prevents the closure from backing off of the container neck. Thus the diametrically opposed gripping ribs, each spaced about ninety degrees from the closure lugs, must be squeezed causing ovalized flexing of the closure and radially outward movement of the lugs allowing the closure lugs to move outward beyond the container neck lugs and the closure to be removed from the container neck.
Extending upwardly from the top wall and radially inset from the peripheral edge is a deflection wall. The upwardly extending wall has a diameter slightly larger than the outer diameter of a container neck thread. Also extending from the top wall is an cutter device comprising a first axial cutter and a second radial cutter. When the closure is inverted and placed over a container having a liner seal over the container rim, the axial cutter punctures the seal causing a the liner seal to tear. The radial cutter spreads the liner apart along the tear caused by the axial cutter and pushes the liner into the container. This action continues as the closure is rotated until a small portion of the uncut liner remains connected to the container rim. In other words the liner is not completely broken by the cutter but instead a portion is left intact to prevent the liner from completely falling into the container and thereby minimizing liner contact with the product in the container.